A simple technique for continuous measurement of time-variable gas transfer in surface waters

Limnology and Oceanography: Methods
By: , and 



Mass balance models of dissolved gases in streams, lakes, and rivers serve as the basis for estimating wholeecosystem rates for various biogeochemical processes. Rates of gas exchange between water and the atmosphere are important and error-prone components of these models. Here we present a simple and efficient modification of the SF6 gas tracer approach that can be used concurrently while collecting other dissolved gas samples for dissolved gas mass balance studies in streams. It consists of continuously metering SF6-saturated water directly into the stream at a low rate of flow. This approach has advantages over pulse injection of aqueous solutions or bubbling large amounts of SF6 into the stream. By adding the SF6 as a saturated solution, we minimize the possibility that other dissolved gas measurements are affected by sparging and/or bubble injecta. Because the SF6 is added continuously we have a record of changing gas transfer velocity (GTV) that is contemporaneous with the sampling of other nonconservative ambient dissolved gases. Over a single diel period, a 30% variation in GTV was observed in a second-order stream (Sugar Creek, Indiana, USA). The changing GTV could be attributed in part to changes in temperature and windspeed that occurred on hourly to diel timescales.
Publication type Article
Publication Subtype Journal Article
Title A simple technique for continuous measurement of time-variable gas transfer in surface waters
Series title Limnology and Oceanography: Methods
DOI 10.4319/lom.2009.7.185
Volume 7
Year Published 2009
Language English
Publisher ASLO
Contributing office(s) Branch of Regional Research-Eastern Region, Toxic Substances Hydrology Program
Description 11 p.
First page 185
Last page 195
Country United States
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